The easy way around this is to install Dropbox instead, it does everything Ubuntu One does but it is a mature program not a beta and you will certainly find it in your applications if you decide to install it.

But if you must have Ubuntu One instead then you will have to accept its drawbacks one of which seems to be (I can't be sure because I don't use it) that it doesn't create a startup menu entry.

If you want to launch it you will have to go to the package manager right click the entry for Ubuntu One and select properties/installed files. Here you have to search through till you find the executable which might be called anything but will start with /bin or /usr/bin or /sbin or /usr/sbin. You will then have to type the entire address into a terminal to launch it. So you might end up with something like: